有时在运行命令时可能会得到意外的结果，因此了解结果背后的“原因”非常有趣。有鉴于此，今天的超级用户问答帖子回答了一位好奇读者的问题。

今天的问答环节是由SuperUser提供的，SuperUser是Stack Exchange的一个分支，是一个由社区驱动的问答网站分组。

问题

超级用户读者Luu Vinh Phuc想知道为什么dir*.*列出所有文件和文件夹：

When I run the dir *.* command, it produces unexpected results. Even files and folders without any dot in the name are listed. For example:

Why is that? Is there any way to only list files with a dot?

为什么dir*.*列出所有文件和文件夹？

答案

超级用户舰队司令部给了我们答案：

The DIR command comes from a time when:

• A period (.) was not allowed as a character in file or folder names
• File and folder names were restricted to 8 characters for names and 3 characters for extensi***

Therefore, by that standard, *.* meant whatever the name and whatever the extension. It did not mean a string containing a “.”, which may or may not have characters before or after the “.”.

Microsoft’s policy is preserving backward compatibility, so that interpretation of *.* is retained. But in Windows PowerShell, *.* means a string containing a “.”, which may or may not have characters before or after the “.”.

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